NCSR Demokritos

Optical particle counter (OPC, Grimm 1.109)

PI: Dr Eleftheriadis Konstantinos ( Operators: Dr. Fetfatzis Prodromos (

Permanent HAC station instrument: OPC Grimm 1.109

The Optical particle counter (OPC) installed at Helmos Mt st. at the end of 2015. OPC is routinely used for real-time aerosol characterization in the particle size range of approximately 0.25–32 μm including 32 size channels. This OPC uses a 655nm laser diode to illuminate the aerosol beam, and a wide-angle collector optic to detect light pulses with a photo diode. The optical arrangement (mean scattering angle 90°) collects the scattered light with a parabolic mirror (120°) on one side and an additional 18◦ on the opposing side.